Strongly recommend this plugin. The formant pitch shifting is pretty much the only way I can get a good femme vocal recording from my testosterone laden cig-y vocal chords. The rest of the Soundtoys collection is pretty fantastic, but replacable. Alterboy is the only plugin I know of that lets you pitch shift the way it does.
My copy is torrented, which is why I can recommend it so freely.
Speaking of that, Izotope has a lot of plugins that can help with trans voices. Those are WAY more complicated than alterboy though so they're loaded suggestions